Effects of changes in the L-type calcium current on hysteresis in restitution of action potential duration

Kathleen M. Guzman, Linyuan Jing, Abhijit Patwardhan

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Background: Electrical restitution and memory of action potential duration (APD) are considered key determinants of stability of activation. Calcium handling also impacts stability of activation via its modification of the above and independently. We determined the effects of reduction in an important calcium current, ICaL, on hysteresis in restitution of APD, which provides assessment of restitution and memory. Methods: Transmembrane potentials were recorded from isolated ventricular tissues from pigs. The pacing protocols consisted of sequential and oscillatory changes in diastolic intervals (DI). Two protocols were used, one where DIs ranged between 100 and 700 ms and the other where DIs ranged between 10 and 290 ms. Verapamil (2 μM/L) was used to reduce ICaL. From the hysteresis observed in restitution, loop area, thickness, overall tilt, and the maximum and minimum delays between DIs and APDs were calculated to obtain measures of memory and restitution. Results: Restitution during sequential and oscillatory changes in DI displayed hysteresis. All measures of hysteresis decreased after reduction in I CaL. The decreases in area, thickness, and overall tilt were most pronounced (50%, 50%, and 33%). Conclusion: Sequential and oscillatory changes in DIs reveal that while the overall slope of restitution of APD decreases with decrease in ICaL, so do measures of memory. Because slopes and memory are considered to have contrasting effects on stability, our results suggest that predicting effects of alteration in ICaL on stability of activation using slope alone may not be adequate. (PACE 2010; 451-459)

Original languageEnglish
Pages (from-to)451-459
Number of pages9
JournalPACE - Pacing and Clinical Electrophysiology
Issue number4
StatePublished - Apr 2010


  • Animal studies
  • Biomedical engineering
  • Electrophysiology - basic

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine


Dive into the research topics of 'Effects of changes in the L-type calcium current on hysteresis in restitution of action potential duration'. Together they form a unique fingerprint.

Cite this